1. Technical Field
This invention relates generally to the field of semiconductors and, more particularly, to utilizing laser annealing techniques for optimizing lithographic processes such as directed self assembly.
2. Related Art
Directed self assembly (DSA) typically requires an annealing processing step, which causes block co-polymers (BCPs) to micro-phase separate and aligns the micro-domains in a thermodynamically preferred orientation. Incomplete processing may cause defects in the desired pattern. Moreover, after processing, the wafers must be cooled back down to room temperature. If this cooling is not properly controlled, defects may be present in the final pattern. One existing approach resolving this is to subject the wafer to very long bakes, or to bake at elevated temperatures, neither of which is desirable. That is, long bake times reduce throughput and increase cost, while high temperature baking risks oxidizing or otherwise damaging the BCP material and preventing self-assembly and full alignment. Laser annealing is a method for effecting substrate baking with very short durations by irradiating a substrate and/or structure at a laser wavelength that is substantially absorbed by the substrate and/or structure. The temperature versus time profile of a laser annealing process can be precisely controlled, for example, by varying the exposure intensity, the laser power, and/or the rate at which the laser is scanned across the substrate, etc.